蓝舌病病毒(BTV)为基因组分节段双链RNA病毒，有26个血清型，基因重排复杂多样，不同血清型毒株致病性差异明显。VP2蛋白决定着BTV血清型，参与病毒的感染与释放过程，其编码基因Seg2在不同血清型毒株间重排致病毒变异机制尚不清楚。本项目在分离获得我国七个血清BTV 101株，建立BTV全基因组扩增、测序与克隆方法的基础上，拟对我国流行的强致病性BTV-1毒株和弱致病性BTV-4毒株进行全基因组扩增与测序，构建两个毒株的全基因组感染性克隆，建立BTV-1和BTV-4毒株反向遗传体系，拯救出BTV-1和BTV-4毒株间Seg2重排变异毒株，通过感染细胞与易感动物，分析亲本毒株与基因重排变异毒株在增殖特性、免疫原性及致病性方面的差异，阐明BTV不同血清型毒株间Seg2重排致病毒变异的机制。研究结果可加深对BTV基因重排致病毒变异的认识，也有助于我国在BTV基因组整体水平上的深入研究。

Bluetongue virus (BTV) possesses a segmented double-stranded RNA genome, existing 26 different serotypes. Reassortment of BTV is variform and complex and there has significant difference in pathogenicity among strains of different serotypes. VP2 protein encoding by Seg2 is the determinant of the BTV serotype,which involved in virus infection and release process. Despite reassortment of Seg2 between different strains of serotypes were founded, the mutation of viral properties along with this reassortment event remains unknown. Based upon our previous isolation of 101 BTV strains belonging to seven different serotypes and established methods for BTV genomic amplification, sequencing and cloning, in this study, full genome of epidemic virulent BTV-1 and avirulent BTV-4 strains of China will be amplified and sequenced. Reverse genetics for the BTV-1 and BTV-4 strains will be developed form infectious clone of these virus complete genomic cDNA. Using the established reverse genetics approach, Seg2 reassortment viruses between virulent BTV-1 and avirulent BTV-4 strains will be rescued. Through in vitro as well as in vivo infection of cultured cells and susceptible animals, the proliferation, immunogenicity and virulence of the reassortants will comparable to the properties of their parent strains to clarify the mechanism of virus mutation caused by Seg2 reassortment between different serotypes BTV strains. The results of this study will further deepen our understanding of BTV mutation caused by reassortment and provide a basis for BTV further research at genomic level.